Support for injection-molding machine

ABSTRACT

Apparatus for molding articles from thermoplastics wherein the moldable plastic material is plasticized and injected into a mold cavity. The plasticizing and injecting unit is pivotally mounted in a frame fixed relative to the mold and the unit may be released at one end of the frame and swung away from the mold to facilitate cleaning.

United States Patent [72] inventors DonaldA.Draudt 27180 Pompton Drive; Herbert '1. Draudt, 28520 Lynhaven, North Olmsted, Ohio 44070 [21 Appl. No. 761,095

[22] Filed Sept. 20, 1968 [45] Patented May 4, 1971 Continuation-impart of application Ser. No. 551,386, May 19, 1966, now Patent No. 3,406,429.

[54] SUPPORT FOR INJECTION-MOLDING MACHINE 4 Claims, 7 Drawing Figs.

[52] U.S. Cl 18/30, 18/12 [51] Int. Cl B291 1100 [50] FieldofSearch 18/300), 30 (NEF), 30 (NFM), 12 (DH), 12 (SV) [56] References Cited UNITED STATES PATENTS 2,274,800 3/1943 Lester ..(l8/30NEM)UX 2,530,262 11/1950 Nelson ..(l8/l2DH)UX Primary Examiner-H. A. Kilby, .lr. Attorney-Bosworth, Sessions, Herrstrom and Cain ABSTRACT: Apparatus for molding articles from thermoplastics wherein the moldable plastic material is plasticized and injected into a mold cavity. The plasticizing and injecting unit is pivotally mounted in a frame fixed relative to the mold and the unit may be released at one end of the frame and swung away from the mold to facilitate cleaning.

SHEET 1 OF 3 PATENTED MAY 4 IBYI minnow 4m 3577.597

SHEET 3 UF 3 INVENTORS.

HER T DRAUDT a DON BM A. DRAUDT J/mdfaan 8 ATTOR 1 SUPPORT FOR INJECTION-MOLDING mounts CROSS REFERENCE TO RELATED APPLICATIONS BACKGROUND OF THE INVENTION Our invention relates to injection molding and more particularly to an improved means for mounting a plasticizing cylinder and injection nozzle in operating relation to a mold so as to facilitate cleaning of the nozzle. i

Injection-molding processes are used .to form many types of plastic material especially thennoplastics such as nylon, polyethylene, vinyl. styrene, polyurethane, delrin and acetate.

Where thermoplastics are used the equipment can be cycled as fast as the material can be heated and plasticized in the cylinder and a measured charge thereof positioned for injection. Fast cycling is particularly desirable in order to avoid overheating and charting, or heating of portions or zones of material for an excessive period of time sufficient to cause decomposition. Methods for obtaining this result however have not been satisfactory in the prior art practices for several reasons.

In many cases rapid cycling of the'injection-molding equipment fails to achieve complete and homogeneous mixing of the plastic material prior to injection so that the injection mechanism does not remove all of the material inthe charging and or forward end of the cylinder during. the molding cycle. As a result residual material may remain in'the cylinder in a heated condition for a time period that may exceedits physical limits and it becomes charred or in some cases decomposed. As a result frequent cleaning of the cylinder bore. and

nozzle is required.

According to priorart practices the cleaning of the nozzle and cylinder bore required partial disassembly of the machine.

This is a laborious procedure and requires shutting down'the equipment for a considerable period of time. Following partial disassembly a cleaning material is run through the cylinder for a few cycles to clean the working surfaces, after which the machine is reassembled.

The apparatus of the present invention reduces the difficulties indicated above and-affords other features and advantages not obtainable from the prior art.

SUMMARY OF THE INVENTION injection-molding machine.

Another object is tosimplify the installation of and cleaning of an injection-molding apparatus of the type disclosed in our copending application, 3,406,429.

These and other objects are accomplished by means of an injection-molding apparatus comprising a frame and a mold in fixed position relative to the frame. The mold block has a face with a sprue formed therein to provide a passage to the molding cavity. A plasticizing cylinder and injection: nozzle .with other associated equipmentare mounted in the frame as a unit for pivotal movement about an axisparallel .tothe sprue face of the mold. The unit has a nozzle spaced from theaxis and adapted to swing with the unit between an operating position in engagement with the sprue face and a pivotally displaced position spaced away from the s'prue face. Also means are provided for fastening the unit to the frame in its operating position.

Other objects, uses and advantages of the invention will be Ser. No. 55l,386 now US. Pat. No.

. 2 BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a sectional view taken through the center of an injcction-molding apparatus embodying the invention;

parts broken away and shown in section,'the injection unitplunger carrier plate in its uppermost position and the rotary drawings.

FIG. 2 is a side elevation of the apparatus of FIG. I with being shown with the nozzle in its operating position; FIG. 3 is a side elevation similar to FIG. 2, showingthe tion stroke;

FIG. 4 is a side elevational view similar 10 nos. 2 and 3 but 1 with the nozzle end of the injection unit released and pivoted away from the frame;

FIG. 6 is another horizontal section similar to FIG. 5, show 'ing an alternate means for securing the lower end of the plasticizing cylinder in position relative to the mold; and

FIG. 7 isstill another horizontal section similar to FIGS. 5

and 6, showing another alternate means for securing the lower end of the plasticizing cylinder in position relative to the mold.

DESCRIPTION OF THE PREFERRED EMBODIMENT v I Referring more particularly to the drawings there is shown a plasticizing andinjecting unit A-adapted for use in connection with a closed die mold B as shown'in FIGS. 2 and 3. The unit A is mounted ina frame C and includes a feed hopper D and a crosshead E. The crosshead E supports the unit A and has trunnions l0.-prov,ided at its opposite ends which are journaled in bearings ill mounted in the frame C. Thus the crosshead E and'the unit A arecapable' of pivotal movement relative to the frame C in accordance with the invention.

FIGS. *1. 2, and 3 show the unit A secured to the frame C in I operating position by a yoke 12 whereas FIG. 4 shows the unit Apivoted aboutthe axis of the crosshead E away from the mold-B to facilitate cleaning of the plasticizing cylinder and nozzle as will be described below.

having piston rods I4 extending downwardly through the crosshead E. Connected to the piston rods I4 is a plunger carrier platelS which carries a tubular injection plunger 16. The plunger carrier plate I5 is guided for reciprocating movement by guide rods I7 which are mounted in fixed position on the crosshead E.

Mounted below the plunger carrier plate 15 is a cylinder plate '20 which is guided for reciprocating movement on the ,guide rods 17 and which supports a plasticizing cylinder 21 having an injection nozzle 22 at its lower end. The cylinder carrier plate20 moves the plasticizing cylinder 21 and the injection nozzle '22 between the position shown in FIG. 2

wherein the bottom of thecylinder 21 rests on a block 23 mounted at the bottom of the frame C, and a position wherein the cylinder -21 and injection nozzle 22 are lifted upward to bring the nozzle 22 out of communication with the sprue of the mold B as.w.ill be more particularly described below.

Axial movement of the plasticizing cylinder 21 is accom# plished by means of lifter rods 24 mounted at opposite ends of the cylinder. carrier plate 20. The lifter rods 24 extend upwardly from the cylinder carrier plate 20 through bushings 26 locatedin the plunger carrier plate 15. The'upper ends of the lifter rods 24 have a radial flange 28 which overlies the top surface of the plunger carrier plate l5 so that during the terminal portion of the upward movement of the plunger carrier plate [5, the lifter rods 26 are pulled upwardly to raise the cylinder plate 20 together with plasticizing cylinder 21.

Mounted .on the cylinder carrier plate 20 above the plasticizing cylinder2l is a guide bushing 29 which receives the tubular injection plunger 16 and guides its reciprocating movement. The bushing 29also serves to close the upper end of the plasticizing cylinder 21.

FIG. 5 is a horizontal section taken on the line 5-5 of FIG."

Mounted for free axial movement within the plasticizing cylinder 21 is a rotary-'member having a shaft 31 which ex-.

tary drive. Located at the lower end-of the shaft 31 within the bore of the plasticizing cylinder 21 is a plasticizing screw 36 having a minor diameter which increases gradually from rear to front. At the lower end of the screw 36 is a mixing head 37.

The operation of the cylinder and plunger 16 1 is best described in our aforementioned copcnding applications and does not form a part of the present invention.

When the nozzle 22 is in the position shown in FIG. 2 the port 38 of the nozzle communicates with a sprue 39 located in the face 40 of the mold adjacent the nozzle (hereinafter called the sprue face). The nozzle port 38 communicates with the lower end of the cylinder bore by means of a passage 4! formed in the plasticizing cylinder 21 to permit plasticized material to flow from the bore'to the nozzle 22 and thence into the mold cavity. The flow of plasticized material from the nozzle 22 to the mold B may be interrupted during the molding cycle by lifting the plasticizing cylinder 21 and nozzle 22 upward to the position shown in FIG. 3 using the hydraulic cylinder 13. In this position the mold block seals the nozzle port 38 and prevents escape of material.

Both the plasticizing cylinder 21' and the nozzle 22 are heated by an external electrical heating jacket during the operation of the equipment to provide desired plasticizing temperatures as is well known in the art.

Downward movement or injecting movement of the plasticizing screw 36 is accomplished by means of the tubular plunger 16 which at an appropriatetime presses against the material at the upperend of the cylinder bore adjacent the inlet port and forces both the material and the screw 36 downwardly throughthe bore. This serves to force plasticized material located at the lower end of the bore outwardly through the passage 4l and the nozzle part 38 into the mold B. The hydraulic cylinders 13 are actuated shortly thereafter I to pull the plunger 16 upwardly out of the cylinder bore to the position shown in FlG. 3 shortly after the mixing head 37 hottoms. During the last portion of the upward movement of the plunger 16, the radial flanges 28 at the ends of the lifter rods 24 are engaged by the plunger carrier plate to lift the plasticizing cylinder injection nozzle 22 out of communication with the mold sprue 39 and prevent the flow of material in either direction.

The lower end of the plasticizing cylinder 2] is secured to the frame C by the yoke 12 which is bolted to lugs 42 welded to opposite sides of the frame C (FIG. 5). A clamping bolt 42 is threaded through the yoke 12 and secured in place by a fastening nut 44. A ball bearing 45 carried in a socket 46 fastenedto the inner end of the clamping bolt 43, bears against a bearing plate 47 welded to the bottom of the plasticizing cylinder 21 and serves to press the nozzle 22 tightly against the sprue face 40 of the mold B (FIG. 5). The ball bearing enables the plasticizing cylinder and nozzle to move up and down between .the 'two positions shown in FIGS. 2 and 3 respectively while still maintaining the necessary pressure forcing the nozzle 22 againstthe sprue face 40.

v FIGS. 6 and 7 show alternate arrangements .for accommodating theaxial movement of the plasticizing cylinder 21 and nozzle 22. ln FlG. 6 a roller bearing 50 bears against a bearing plateSl on the cylinder 2 l the roller 50 being carried I in a roller carrier 52. FIG. 7 shows a similararrangement wherein a concave roller bearing 53 is used to avoid the need for a bearing plate, the bearing surface being formed to match When the plasticizing cylinder 2l and nozzle 22 are to be v cleaned the operation is stopped at a point in the cycle when capable of free axial movement during the operation of the ro-' mounted in said frame for pivotal movement about a horizonthe nozzle 22 'is raised to the position shown in FIG. 3 To release the nozzle 22, plasticizing cylinder 21 and associated parts of the unit A, the bolts which secure the yoke 12 to the frame C are removed. Then the entire unit A which includes the nozzle 22 and plasticizing cylinder 21 may be pulled back to the position shown in FIG. 4 and held in position by inserting a spacing block between the frame and the outwardly pivoted unit. With the unit A in this'position access is provided to the nozzle 22 and the machine may be cycled as often as I desired to. remove the plastic material remaining in .the cylinder and nozzle and also to pass suitable cle'aning'lluid through a sufficient number of cycles to clean the working su r faces and remove all of the charred material.

When this is accomplished the spacer block may be removed and the unit A swung back to its operating. position shown in FIG. 3. Then the yoke 12 is positioned andbolted to the lugs 42 and the clamping bolt 43 is tightened down so that V the nozzle 22 is firmly held against the sprue face 40 of the mold B. The machine is then cycled a sufficient number of times to prepare a plasticized charge of material in the plasticizing cylinder at the lower end thereof preparatory to its injection into the mold cavity. Themachine is then ready to be put into operation once again. v

It will be understood that our invention has been shown and described with reference to a preferred embodiment thereof which is intended for the purpose of illustration rather than limitation .and that variations and modifications will be apparent to those skilled in the art within the intended spirit and scopc of our teaching, wherefor we do not want our patent to be limited to the form or forms of apparatus herein specifically illustrated and described nor in any manner inconsistent with the progress by which the art has been promoted by our invention We claim: I

1. Apparatus for injection molding of plastics comprisinga frame, a mold fixed relative to said frame and having a face with a sprue formed therein, a-plasticizing andinjecting unit tal axis parallel to said sprue face and spaced above said mold, said unit having a nozzle spaced below said axis and adapted to swing with said unit between an operating position in engagement with said sprue face and a retracted position substantially spaced away from said sprue face, and means for fastening said unit to said frame when said nozzle is in operating position.

2. Apparatus as defined in claim 1 wherein said plasticizing and injecting unit is supported on a trunnion bar, the trunnions at the opposite ends of said bar being journaled in said frame.

' 3. Apparatus as defined in claim 1 wherein said nozzle when in said operating position is movable linearly parallel said sprue face between a position wherein the nozzle port rev gisters with said mold sprue and a position whercin said nozzle roller means carried by said adjustable member and engageable with said plasticizing and injecting unit to accommodate said linear movement of said nozzle. 

2. Apparatus as defined in claim 1 wherein said plasticizing and injecting unit is supported on a trunnion bar, the trunnions at the opposite ends of said bar being journaled in said frame.
 3. Apparatus as defined in claim 1 wherein said nozzle when in said operating position is movable linearly parallel said sprue face between a position wherein the nozzle port registers with said mold sprue and a position wherein said nozzle port is out of registration with said mold sprue to block the exit of plasticized material.
 4. Apparatus as defined in claim 3 wherein said means for fastening said plasticizing and injecting unit to said frame comprises a yoke fastened to said frame on opposite side of said plasticizing and injecting unit an adjustable member threadedly mounted in said yoke intermediate the ends thereof and being operable to force said plasticizing and injecting unit toward said mold to press said sprue face and roller means carried by said adjustable member and engageable with said plasticizing and injecting unit to accommodate said linear movement of said nozzle. 